1) Field of the Invention
The present invention relates to a technique applied when a plurality of processing apparatuses share a plurality of file storing apparatuses through a file controlling apparatus. In particular, the present invention relates to a method for controlling re-connection of a channel interface between a processing apparatus and a file controlling apparatus due to generation of a re-connecting factor, after the channel interface has been temporarily made to be in a disconnected state since the processing apparatus cannot access to the file storing apparatus when accessing to the file storing apparatus, and a file controlling apparatus for realizing the above method.
2) Description of the Related Art
When a plurality of processing apparatuses share a plurality of file storing apparatuses, there is generally provided, between between the processing apparatuses and the file storing apparatuses, a file controlling apparatus which controls an accessing operation on each file storing apparatus in response to a command from each processing apparatus. The processing apparatus is, for example, a CPU, whereas the file storing is, for example, a device (DASD: Direct Access Storage Device) such as a magnetic disk or the like. Hereinafter, the file controlling apparatus will be referred as an FCU, whereas the file storing apparatus will be referred simply as a device, occasionally.
In a system having the above FCU, a CPU locks out an access from another CPU by a reserve command in order to read data from each device shared by other CPUs or write data in the device, then issues a read command or a write command when an occupancy of the device is established.
The FCU is a shared device. When a certain CPU occupies the device, the FCU thereafter reports device busy to a command from another CPU to disconnect that CPU. When the device is released from the occupied state by a release command from the CPU having issued the reserve command, the FCU re-connects the CPU (channel) to which device busy has been reported (device end interruption due to release: a first re-connecting factor).
When a read command process or a write command process involves an operation (staging operation) of the magnetic disk, the FCU disconnects a CPU having issued a read command or a write command, then re-connects the CPU (channel) when the staging operation of the magnetic disk is completed (device end interruption due to staging completion: a second re-connecting factor). Incidentally, the staging operation is to read data from a device holding the data into a cache memory when the data to be read or to be written does not exist in the cache memory in the FCU.
Now, a structure of a general FCU will be described with reference to FIG. 23. FIG. 23 is a block diagram showing a structure of a general FCU. As shown in FIG. 23, the FCU 1 is provided between CPUs 2-0 and 2-1 and devices 3-0 through 3-2 in order that a plurality (two in FIG. 23) of the CPUs 2-0 and 2-1 share a plurality (three in FIG. 23) of the devices 3-0 through 3-2 to control an access operation on each of the devices 3-0 through 3-2 in response to a command from each of the CPUs 2-0 and 2-1. Incidentally, when either one of the two existing CPUs is specified, a reference character 2-0 or 2-1 is used, or when there is no need to specify, a reference character 2 is used. Similarly, when any one of the three existing devices is specified, a reference character 3-0, 3-1 or 3-2 is used, or when there is no need to specify, a reference character 3 is used.
The FCU 1 comprises CAs (Channel Adapter) 11-0 through 11-3, an RM (Resource Manager) 12, a TS (Table Storage) 13, a CFE (Cache Function Engine) 14, a cache memory 15, DAs (Device Adapter) 16-0 through 16-2, a command bus 17 and a data bus 18. Incidentally, when any one of the four existing CAs is specified, a reference character 11-0, 11-1, . . . or 11-3 is used, or when there is no need to specify, a reference character 11 is used. Similarly, when any one of the three existing DAs is specified, a reference character 16-0, 16-1 or 16-2 is used, or when there is no need to specify, a reference character 16 is used.
Each of the CAs 11-0 through 11-3 is a module in charge of control on an interface with a corresponding CPU 2-0 or 2-1 via a channel interface. Each of the CPUs 2-0 and 2-1 has, for example, two channels (CH) 2a and 2b. In an example shown in FIG. 23, channels 2a and 2b of the CPU 2-0 are connected to the CAs 11-0 and 11-1, respectively. Channels 2a and 2b of the CPU 2-1 are connected to the CAs 11-2 and 11-3, respectively.
The RM 12 is a module in charge of resource management with respect to a basic operation. The TS 13 is a memory used as a table for resource management. The RM 12 and the TS 13 function as a controlling unit for controlling re-connection of a channel interface due to generation of a re-connecting factor, after a channel interface with one of the two CPUs 2-0 and 2-1 is temporarily made to be in a disconnected state since the CPU 2 cannot access to one of the three devices 3-0, 3-1 or 3-2 when the CPU 2 accesses to the device 3, as will be described with reference to FIGS. 24 through 46.
The CFE 14 is a module in charge of management of the cache memory 15. Each of the DAs 16-0 through 16-2 is a module in charge of control on an interface with a corresponding device 3-0, 3-1 or 3-2 such as a magnetic disk or the like.
The command bus 17 is used to exchange commands among the CA 11, the RM 12, the CFE 14 and the DA 16. The data bus 18 is used to exchange data among the CA 11, the CFE 14, the cache memory 15 and the DA 16.
Next, functional structures of the RM 12 and the TS 13 controlling re-connection of a channel interface will be described with reference to FIGS. 24 through 29. FIG. 24 is a block diagram showing a functional structure of a general RAM 12/TS 13. FIGS. 25 through 29 are diagrams illustrating a reserve management table 31, a device busy report management table 32, a device end report management table 33, a task control block (TCB) 34 and a staging completion report management table (queue) 35.
As shown in FIG. 24, the TS 13 holds the reserve management table 31, the device busy report management table 32, the device end report management table 33, the TCB 34 and the staging completion report management table 35. The RM 12 functions as a mechanism (re-connecting mechanism due to device release) executing a re-connecting process using the device busy report management table 32 and the device end report management table 33 of the TS 13 when the above first re-connecting factor generates. The RM 12 also functions as a mechanism (re-connecting mechanism due to staging completion) executing a re-connecting process using the staging completion report management table 35 of the TS 13 when the above second re-connecting factor generates.
The reserve management table 31 is configured as shown in FIG. 25 to manage a device 3 occupied by a CPU 2. Incidentally, in the table 31, xe2x80x9cCA0xe2x80x9d through xe2x80x9cCA3xe2x80x9d correspond to the CA 11-0 through the CA 11-3, respectively, and device numbers 0 through 2 correspond to the devices 3-0 through 3-2, respectively. For example, when a reserve command for the device 3-0 is issued from the channel 2a of the CPU 2-0 so that the CPU 2-0 can occupy the device 3-0, the RM 12 sets xe2x80x9c1xe2x80x9d at the intersection of xe2x80x9cCA0xe2x80x9d and device number 0 in the table 31 (refer to FIG. 36).
The device busy report management table 32 is configured as shown in FIG. 26 to manage a CPU 2 to which the RM 12 reports device busy through a corresponding CA 11, and a device 3 that the CPU 2 intends to occupy. Incidentally, in the table 32, xe2x80x9cCA0xe2x80x9d through xe2x80x9cCA3xe2x80x9d correspond to the CA 11-0 through CA 11-3, respectively, and device numbers 0 through 2 correspond to the devices 3-0 through 3-2, respectively, as well. For example, when a reserve command for the device 3-0 is issued through the channel 2a (CA 11-2) of the CPU 2-1 in a state where the CPU 2-0 occupies the device 3-0 through the channel 2a (CA 11-0) as stated above, the RM 12 makes a device busy reports, controls the CA 11-2 to disconnect the channel 2a of the CPU 2-1, and sets xe2x80x9c1xe2x80x9d at the intersection of xe2x80x9cCA2xe2x80x9d and device number 0 in the table 32 (refer to FIG. 38).
The device end report management table 33 is configured as shown in FIG. 27 to manage a CPU 2 to which the RA 12 should report device end through a corresponding CA 11. Incidentally, in the table 33, xe2x80x9cCA0xe2x80x9d through xe2x80x9cCA3xe2x80x9d correspond to the CA 11-0 through CA 11-3, respectively, and device numbers 0 through 2 correspond to the devices 3-0 through 3-2, respectively, as well. For example, when the CPU 2-0 issues a release command for the device 3-0 through the channel 2a (CA 11-0) after device busy is reported and the channel 2a of the CPU 2-1 is disconnected as stated above, the RM 12 (re-connecting mechanism 21) deletes an entry in the reserve management table 31, and refers to the device busy report management table 32 to confirm whether or not there is any CPU 2 to which a device busy report with respect to a device 3 released from occupancy has been made. When there is a CPU 2, the RM 12 copies data of the device busy report management table 32 to the device end report management table 33, and deletes the entry in the device busy report management table 32. Whereby, xe2x80x9c1xe2x80x9d is set at the intersection of xe2x80x9cCA2xe2x80x9d and device number 0 in the table 33 (refer to FIG. 44). The RM 12 (re-connecting mechanism 21) refers to the device end report management table 33, controls the CA 11-2 so as to re-connect the channel 2a of the CPU 2-1 at a timing to be described with reference to FIG. 34, and makes a device end report.
The TCB 34 is configured as shown in FIG. 28, and made each time the RM 12 executes a task in response to a command and deleted each time the RM 12 completes the task. The TCB 12 includes information or the like relating to a task, and used to control the task. In the TCB 34, there are held contents (type) of a command from a CPU 2, a number of the CA 11 which has received the command, a number of the device 3 that is an object of the command and a re-connecting factor, with a task number attached to each task. As re-connecting factor, there is held an effect that a staging operation is completed (that is, the second re-connecting factor generates) after the FCU 1 shifts to the staging operation when processing a read command/write command. More concretely, when the staging operation is completed, xe2x80x9c1xe2x80x9d, for example, is set as re-connecting factor in the TCB 34 by the RM 12.
The staging completion report management table 35 is configured as shown in FIG. 29 to manage a TCB number of a task that should undergo a re-connecting process due to completion of staging. In the table 35, there are entered TCB numbers of tasks to each of which a re-connecting factor is set due to completion of the staging operation by the RM 12 as stated above in the order in which the tasks should undergo the re-connecting process (refer to FIG. 46). The RM 12 (re-connecting mechanism 22) refers to the staging completion report management table 35, and performs the re-connecting process due to completion of staging at a timing to be described with reference to FIG. 34.
Next, detailed operations of the above RM 12 and the TS 13 will be described with reference to FIGS. 30 through 46.
First, flows of the operations of the RM 12 and the TS 13 will be described with reference to flowcharts shown in FIGS. 30 through 34.
FIG. 30 is a flowchart illustrating an operation of the RM 12 when the RM 12 receives a reserve command. As shown in FIG. 30, the RM 12 makes a TCB 34 about the reserve command when receiving the reserve command (Step A11), refers to the reserve management table 31, and determines whether or not a device 3 that is an object of the reserve command is reserved by another CPU 2 (another path, another channel) (Step A12).
When the device 3 is not reserved by another path (NO route at Step A12), the RM 12 performs a reserving process on the device 3 that is an object of the reserve command (Step A13), and deletes the TCB 34 with respect to the reserve command (Step A15). In the reserving process, the RM 12 sets xe2x80x9c1xe2x80x9d at the intersection of a device number of the device 3 that is an object of reserve and a CA 11 having received the reserve command.
When the device 3 that is an object of the reserve command is already reserved by another path (YES route at Step A12), the RM 12 makes an entry about the reserve command in the device busy report management table 32, makes a device busy report to the CPU 2 that is a source of the reserve command, then controls the CA 11 so as to disconnect a channel interface with the CPU 2 (Step A14). After that, the RM 12 deletes the TCB 34 with respect to the reserve command (Step A15)
FIG. 31 is a flowchart illustrating an operation of the RM 12 when the RM 12 receives a release command. As shown in FIG. 31, the RM 12 makes a TCB 34 with respect to a release command when receiving the release command from a CPU 2 occupying a device 3 (Step A21), deletes an entry (setting of xe2x80x9c1xe2x80x9d) corresponding thereto in the reserve management table 31. When there is an entry in the device busy report management table 32 that a device busy report with respect to the device 3 whose occupancy is to be released is made, the RM 12 moves the entry information in the device busy report management table 32 to the device end report management table 33 (Step A22). After that, the RM 12 deletes the TCB 34 with respect to the release command (Step A23).
FIG. 32 is a flowchart illustrating an operation of the RM 12 when the RM 12 receives a read command. As shown in FIG. 32, when the RM 12 receives a read command from a CPU 2 occupying a device 3, the RM 12 makes a TCB 34 with respect to the read command (Step A31), and determines through the CFE 14 whether or not data to be read exists in the cache memory 15 (Step A32).
When the data to be read exists in the cache memory 15 (YES route at Step A32), the RM 12 transfers the data through a corresponding CA 11 to the CPU 2 (Step A33), then deletes the TCB 34 with respect to the read command (Step A34).
When the data to be read does not exist in the cache memory 15 (NO route at Step A32), the RM 12 reports channel end to the CPU 2 through the CA 11, requests a corresponding DA 16 to perform staging on the device 3, and shifts to a staging completion report waiting process to be described with reference to FIG. 33 (Step A35). On this occasion, the TCB 34 with respect to the read command is not deleted but kept held.
FIG. 33 is a flowchart illustrating the staging completion report waiting process by the RM 12. As shown in FIG. 33, the RM 12 waits for a staging completion report from a DA 16 to which the RM 12 makes a request for staging (Step A41) When the RM 12 receives the staging completion report from the DA 16 (YES route at Step A41), the RM 12 sets xe2x80x9cstaging completionxe2x80x9d, that is, xe2x80x9c1xe2x80x9d to the re-connecting factor of a TCB 34 with respect to a corresponding read command (Step A42).
The RM 12 enters a TBC number of the task to which the re-connecting factor has been set at Step A42 in the staging completion report management table 35 (Step A43), and waits for the data read out in the staging operation to be transferred to a CPU 2 by a corresponding CA 11 according to an idle loop to be described with reference to FIG. 34 (Step A44). When the CA 11 completes transfer of the data (YES route at Step A44), the RM 12 deletes the TCB 34 with respect to the read command waiting for the staging completion report (Step A45).
FIG. 34 is a flowchart illustrating a process using the idle loop by the RM 12. As shown in FIG. 34, the RM 12 determines at any time using the idle loop whether or not a TCB number is entered in the staging complete report management table 35. In other words, the RM 12 determines whether or not the second re-connecting factor generates (Step A51). The RM 12 then determines whether or not there is any entry information in the device end report management table 33, that is, whether or not the first re-connecting factor generates (Step A53).
Generally, re-connecting due to staging completion is performed in preference to re-connecting due to device release. For this, when a TCB number is entered in the staging completion report management table 35 (YES route at Step A51), the RM 12 refers to a TCB 34 at that TCB number, re-connects a CPU 2 corresponding thereto, requests the CA 11 to make a staging completion report to the CPU 2, and deletes the TCB number in the staging completion report management table 35 (Step A52).
When a plurality of TCB numbers are entered in the staging completion report management table 35, the above re-connecting process is performed on all the TCB numbers. When all the TCB numbers entered in the staging completion report management table 35 are consumed (NO route at Step A51), the RM 12 determines presence/absence of entry information in the device end report management table 33. When there is any entry information (YES route at Step A53), the RM 12 refers to the entry information, re-connects a CPU 2 corresponding thereto, requests the CA 11 to make a device end report to the CPU 2, and deletes the entry information in the device end report management table 33 (Step A54).
Next, concrete contents of entries in the tables 31 through 33 and 35, and the TCB 34 will be described with reference to FIGS. 35 through 46.
For example, when a reserve command for the device 3-0 is issued from the channel 2a of the CPU 2-0 in a state where none is entered in the tables 31 through 33 and 35, and the TCB 34, xe2x80x9c0xe2x80x9d is entered as device number, xe2x80x9c0xe2x80x9d as CA number and xe2x80x9creservexe2x80x9d as command at TCB number 1 in the TCB 34, as shown in FIG. 35. Since any device 3 is not yet reserved on this occasion, a reserving process is performed on the device 3-0, so that xe2x80x9c1xe2x80x9d is set at the intersection of device number 0 and xe2x80x9cCA0xe2x80x9d in the reserve management table 31, as shown in FIG. 36. After that, the TCB 34 at TCB number 1 made as shown in FIG. 35 is deleted.
When a reserve command for the device 3-0 is issued through the channel 2a (CA 11-2) of the CPU 2-1 in a state where the CPU 2-0 occupies the device 3-0 through the channel 2a (CA 11-0) as above, xe2x80x9c0xe2x80x9d is entered as device number, xe2x80x9c2xe2x80x9d as CA number and xe2x80x9creservexe2x80x9d as command at TCB number 1 in the TCB 34, as shown in FIG. 37. Then, since the device 3-0 is already occupied by the CPU 2-0, device busy is reported to the CPU 2-1 so as to disconnect a channel interface with the CPU 2-1, and xe2x80x9c1xe2x80x9d is set in the intersection of xe2x80x9cCA2xe2x80x9d and device number 0 in the device busy report management table 32, as shown in FIG. 38. After that, the TCB 34 at TCB number 1 made as shown in FIG. 37 is deleted.
Following that, when the CPU 2-1 reads data in the device 3-1, a reserve command for the device 3-1 is issued from the channel 2a of the CPU 2-1, and xe2x80x9c1xe2x80x9d is entered as device number, xe2x80x9c3xe2x80x9d as CA number and xe2x80x9creservexe2x80x9d as command at a TCB number 1 in the TCB 34, as shown in FIG. 39. Since the device 3-1 is not reserved at this time, the reserving process on the device 3-1 is performed, so that xe2x80x9c1xe2x80x9d is set at the intersection of device number 1 and xe2x80x9cCA3xe2x80x9d in the reserve management table 31, as shown in FIG. 40. After that, the TCB 34 at the TCB number 1 made as shown in FIG. 39 is deleted.
When the CPU 2-1 having reserved the device 3-1 issues a read command, xe2x80x9c1xe2x80x9d is entered as device number, xe2x80x9c3xe2x80x9d as CA number and xe2x80x9creadxe2x80x9d as command at TCB number 1 in the TCB 34 as shown in FIG. 41. When data to be read does not exist in the cache memory 15 on this occasion, the staging operation on the device 3-1 is initiated. During which, the TCB 34 with respect to the read command is not deleted but kept held.
When the CPU 2-0 having reserved the device 3-0 issues a release command through the CA 11-0 in the above state, xe2x80x9c0xe2x80x9d is entered as device number, xe2x80x9c0xe2x80x9d as CA number and xe2x80x9creleasexe2x80x9d as command at TCB number 2 in the TCB 34, as shown in FIG. 42. Then, xe2x80x9c1xe2x80x9d having been set at the intersection of device number 0 and xe2x80x9cCA0xe2x80x9d is deleted in the reserve management table 31 as shown in FIG. 43, entry information in the device busy report management table 32 is moved to the device end report management table 33 as shown in FIG. 44, after that, the TCB 34 at TCB number 2 made as shown in FIG. 42 is deleted.
When the staging operation is completed, xe2x80x9cstaging completionxe2x80x9d (practically, xe2x80x9c1xe2x80x9d) is set to re-connecting factor at TCB number 1 in the TCB 34, as shown in FIG. 45, and TCB number 1 is entered in the staging completion report management table 35, as shown in FIG. 46.
The RM 12 monitors the staging completion report management table 35 and the device end report management table 33 using the idle loop described above with reference to FIG. 34. When recognizing that TCB number 1 is registered in the staging completion report management table 35 as shown in FIG. 46, the RM 12 refers to the TCB 34 at TCB number 1, requests the CA 11-3 to make a staging completion report, after that, deletes TCB number 1 in the staging completion report management table 35 and deletes the TCB 34 at TCB number 1.
When no entry information exists in the staging completion report management table 35, the RM 12 refers to the device end report management table 33. When information as shown in FIG. 46 is entered, for example, the RM 12 requests the CA 11-2 to make a device end report with respect to the device 3-0, after that, deletes the entry information in the device end report management table 33.
When the FCU 1 shifts to the staging operation in response to a read command, the FCU 1 generally reports channel end to a CPU 2 having issued the read command and temporarily disconnects the CPU 2, so that the CPU 2 gets into a state where the CPU 2 waits for a staging completion report. The state where the CPU 2 waits for a staging completion report is a state for the CPU 2 where the CPU 2 waits for one I/O processing to be completed. The staging operation is completed within a relatively short period, so that time monitoring is performed in a predetermined time corresponding thereto (about 30 second, for example). When the predetermined time is elapsed, a resetting process is performed.
On the other hand, in the case where a device 3 accessed by a certain CPU 2 is occupied by another CPU 2 so that the FCU 1 makes a device busy report to temporarily disconnect the CPU 2 and the CPU 2 therefore gets into a state where the CPU 2 waits for a device end report, a time period for which the device is occupied is relatively long, thus time monitoring is performed for a predetermined time (3 minutes, for example) corresponding thereto and the resetting process is performed when the predetermined time is elapsed.
As stated above, the staging operation is completed within a much shorter time than a time for which the device is occupied, and the FCU 1 and a CPU 2 in a state where the CPU 2 waits for a staging completion report are disconnected in a channel end state but have to be certainly re-connected thereafter. For this, the staging completion report and the device end report are separately managed, in general. Re-connecting due to staging completion (staging completion report) is performed in preference to re-connecting due to device release (device end report).
In these years, the number of devices 3 to be managed by the FCU 1 is considerably increased (256, for example). In such case, reading processes on a number of devices 3 are concurrently performed so that a number of staging operations are concurrently performed, which often leads to an increase of the number of staging completion reports, and a queue of a plurality of TCB numbers in the staging completion report management table 35. Under such circumstances, a staging completion report is made in preference to a device end report until TCB numbers entered in the staging completion report management table 35 are consumed, which brings a situation where a device end report cannot be hardly made.
To cope with this, it is possible to make a device end report in preference to a staging completion report once in several occasions. However, since the FCU 1 does not recognize the order in which the FCU 1 should re-connect due to device release (the order in which device end reports should be made), only a device end report with respect to a certain device 3 is prone to be delayed when reserve/release frequently occurs on that device 3, leading to a partiality for the devices 3 about which device end reports can be made to the CPUs 2.
In the light of the above problem, an object of the present invention is to provide a channel interface re-connection controlling method and a file controlling apparatus, in which a re-connecting process can be performed in the order in which re-connecting factors have generated irrespective of a type of each re-connecting factor so that both a device end report due to release and a staging completion report are executed without delay and postponement.
The present invention therefore provides a method used in a system having a file controlling apparatus provided between a plurality of processing apparatuses and a plurality of file storing apparatuses to control an accessing operation on each of the file storing apparatuses in response to a command from each of the processing apparatuses in order that the plurality of processing apparatuses share the plurality of file storing apparatuses, the method for controlling re-connection of a channel interface between one of the plurality of processing apparatuses and the file controlling apparatus due to generation of a re-connecting factor, after the channel interface therebetween has been temporarily made to be in a disconnected state since the processing apparatus cannot immediately access to one of the plurality of file storing apparatuses when the processing apparatus accesses to the file storing apparatus, the channel interface re-connection controlling method comprising the steps of monitoring generation of the re-connecting factors, storing the order of generation of the re-connecting factors, and re-connecting the channel interface between the processing apparatus relating to each of the re-connecting factors and the file controlling apparatus relating to each of the re-connecting factors in the stored order of generation of the re-connecting factors.
The above re-connecting factors includes a first re-connecting factor generating when the file storing apparatus is released from another processing apparatus, after the file controlling apparatus makes a busy report to the former processing apparatus and a channel interface between the former processing apparatus and the file controlling apparatus has been temporarily made to be in a disconnected state since the file storing apparatus is occupied by the latter processing apparatus when the former processing apparatus accesses to the file storing apparatus, and a second re-connecting factor generating when the file controlling apparatus completes a staging operation, after a channel interface between the processing apparatus and the file controlling apparatus has been temporarily made to be in a disconnected state since the file controlling apparatus shifts to the staging operation on a file storing apparatus in response to a command from a certain processing apparatus.
The present invention further provides a file controlling apparatus provided between a plurality of processing apparatuses and a plurality of file storing apparatuses in order that the plurality of processing apparatuses share the plurality of file storing apparatuses to control an accessing operation on each of the file storing apparatuses in response to a command from each of the processing apparatuses, the file controlling apparatus comprising a controlling unit for controlling re-connection of a channel interface between one of the plurality of processing apparatuses and the file controlling apparatus due to generation of a re-connecting factor, after the channel interface between the processing apparatus and the file controlling apparatus has been temporarily made to be in a disconnected state since the processing apparatus cannot immediately access to one of the plurality of file storing apparatuses when the processing apparatus accesses to the file storing apparatus, and a generation order storing unit for storing the order of generation of the re-connecting factors, wherein the controlling unit monitors generation of the re-connecting factors, stores the order of generation of the re-connecting factors in the generation order storing unit, and re-connects the channel interface between the processing apparatus relating to each of the re-connecting factors and the file controlling apparatus relating to each of the reconnecting factors in the order of generation stored in the generation order storing unit.
The above re-connecting factors includes a first re-connecting factor generating when the file storing apparatus is released from another processing apparatus, after the file controlling apparatus makes a busy report to the former processing apparatus and a channel interface between the former processing apparatus and the file controlling apparatus has been temporarily made to be in a disconnected state since the file storing apparatus accessed by the former processing apparatus is occupied by the latter processing apparatus, and a second re-connecting factor generating when the file controlling apparatus completes a staging operation, after a channel interface between the processing apparatus and the file controlling apparatus has been temporarily made to be in a disconnected state since the file controlling apparatus shifts to the staging operation on a file storing apparatus in response to a command from a certain processing apparatus.
The controlling unit may determine that the first re-connecting factor generates when a release command has been received from the latter processing apparatus, and enters the first re-connecting factor in the generation order storing unit. In which case, the controlling unit may manage the busy report using a task control block, and enter a number of the task control block in the generation order storing unit when the first re-connecting factor generates. The above file controlling apparatus may further comprise a busy report order storing unit for storing the order in which the busy reports have been made.
Still further, the controlling unit may determine that the second re-connecting factor generates when a completion report about the staging operation has been received, and enters the second re-connecting factor in the generation order storing unit. In which case, the controlling unit may manage a state of waiting for the completion report about the staging operation using a task control block, and enter a number of the task control block in the generation order storing unit when the second re-connecting factor generates.
According to the channel interface re-connection controlling method and the file controlling apparatus of this invention, it is possible to perform a re-connecting process in the order in which re-connecting factors have generated irrespective of a type of each re-connecting factor. It is therefore possible to execute a device end report due to release and a staging completion report without delay and postponement. Consequently, device end reports can be made in the order in which devices have been released, thereby certainly avoiding postponement of a device end report heretofore occurring due to an increase of the number of staging completion reports.